The invention relates to a process for removal of hydrogen sulfide and mercaptan contaminants from a fluid, especially from hydrocarbons such as refinery fuel gas, LPG, cracked gasoline, straight run gasoline, natural gasoline, and heavier hydrocarbon distillates including kerosene, fuel oil and the like.
Sulfur contaminants in the form of hydrogen sulfide and mercaptan are undesirable for a large number of reasons. For example, hydrogen sulfide can be hazardous to persons exposed thereto, and mercaptan is objectionable due to a strong odor. Furthermore, these components can be objectionable due to their chemical reaction with other hydrocarbons or fuel system components.
There have been many attempts to provide processes for the removal of mercaptan contaminants. Early processes included treatment of the hydrocarbon fractions with caustic, clays, and hydrotreating. One such process is the UOP Merox process, which was announced in 1959 (Oil and Gas Journal, Oct. 26, 1959). This process used a catalyst which was soluble in caustic, or alternatively held on a support, to oxidize mercaptans to disulfides in the presence of oxygen and caustic. A main disadvantage of caustic treatment is that disposal of spent caustic is undesirable for environmental reasons.
Other chemical processes for the treatment of hydrocarbon feeds containing sulfur compounds and acidic components have involved purely chemical reactions such as scrubbing with mono or diethanolamine or counter current extraction using a hot potassium carbonate solution. Amine systems are, unfortunately, high in operation cost and further characterized by corrosive nature of the absorbing liquids used, and the inability to sufficiently remove mercaptan.
It is therefore the primary object of the present invention to provide a process for scavenging hydrogen sulfide and mercaptan contaminants from a fluid which avoids the need for caustic treatment.
It is a further object of the present invention to provide a process for scavenging sulfur contaminants from a fluid which effectively scavenges both hydrogen sulfide and mercaptan contaminants.
Other objects and advantages of the present invention will appear hereinbelow.